When it comes to dining like a Gotham insider, you probably know all about food trucks and the secret speakeasies. But what about pop-up restaurants?

Born of the flailing economy, pop-up restaurants arrived on the New York scene a little more than a year ago. Chefs and would-be entrepreneurs squeezed by the recession were looking for ways to gain exposure and test new businesses with little overhead.

FOR THE RECORD:Pop-up restaurants: A story in the March 7 Travel section on New York's pop-up restaurants--eating places that "pop up" in the site of another business and are not permanent--incorrectly reported the closing date of a temporary restaurant called Sandwiched. This pop-up inside the Whitney Museum of American Art will remain open through the fall.

The popularity of these restaurants and food shops should be no surprise. In a town that fetishizes the newest, the ephemeral and the "thing that nobody else has done yet," a restaurant or shop that's open only for a limited time has a built-in cool factor.

Like many food trends, pop-ups started largely in Brooklyn, where you can begin your tour in the hipster haven of Williamsburg.

Here, you'll find Bep. At a little more than a year old, this Vietnamese restaurant operates out of an unassuming French coffee shop, Simple Café.

"I was supposed to open a place with a partner, and we split, so I no longer had enough money," An Nguyen Xuan says.

"I was looking to find a way to test it out, and I walked by Simple Café and saw that they are closed on Mondays," he explains. "The owner, she is French, and I am French Vietnamese, so I thought we would get along. We started off just doing Mondays, and after eight months we added more nights."

Bep now takes over Simple Café three days a week. The menu is filled with fresh Vietnamese classics. Although the food is tasty, the allure, of course, is that it's not really a restaurant. There's no sign on the door announcing that it serves Vietnamese food.

Lesson No. 1: Don't expect to stumble on a pop-up. Like the raves of the '90s, you have to know it's there.

The same is true of AsiaDog, because it is seasonal. In the summertime, AsiaDog takes over Trophy Bar, a neighborhood watering hole in Williamsburg, on Tuesday evenings. AsiaDog serves hot dogs topped with Asian-influenced condiments. One slathered with Japanese curry and housemade kimchi apples is popular, as is the bánh mi-style hot dog and the bulgogi-inspired burger. The atmosphere is low-key, like a casual backyard barbecue, with chef-owner Melanie Campbell at the grill.

Lesson No. 2: Expect to wait at a pop-up, especially when beer is involved.

Trophy Bar was the first of many pop-ups for AsiaDog. Last summer, it appeared at different bars, mostly in Manhattan, almost every night. Campbell is getting ready to announce this summer's schedule, but meanwhile, you can try the dogs every weekend at the Brooklyn Flea Market in Fort Greene and at Bell House, a performance space in the Gowanus neighborhood of Brooklyn that books AsiaDog whenever there are sold-out shows.

Like any underground event, these pop-ups are often announced at the last minute, and the only way to track them is on Twitter. Even the AsiaDog website doesn't always have its latest schedule.

Lesson No. 3: Stay current on Twitter.

Bep and AsiaDog have had a longer shelf life than some pop-ups, which are by design short-lived. During Valentine's Day week, two sweet shops popped up in New York City. Dorie Greenspan, the cookbook author, and her son Josh took over part of a hair salon on the Upper East Side to try out her cookie business. It wasn't totally random; Josh gets his hair cut at the salon, and Greenspan is known for her cookie recipes.

The under-the-radar nature of pop-ups means that sometimes the usual paperwork of brick-and-mortar stores is ignored. Although the finicky might wonder about the wisdom of selling — or buying — food in a salon, Josh says there were no issues. The cookies, individually wrapped in cellophane bags, were sold where no hair-cutting was taking place. They sold out progressively earlier each of the six days the pop-up was open, and now the Greenspans are looking for space to open a permanent bakery in the fall.

Lesson No. 4. Go at opening time.

Kumquat Cupcakery and Liddabit Sweets, two Brooklyn-based artisans that sell primarily at the Brooklyn Flea Market and on their own websites, temporarily popped up in the space previously occupied by a vintage clothing and housewares store in Greenpoint, another Brooklyn neighborhood. Kumquat too often sold out of its miniature "cakelettes," and Liddabit hopes to someday open a more permanent brick-and-mortar business.

And, as with any good trend, the establishment has caught on.

Danny Meyer, one of the city's biggest restaurateurs, has launched a pop-up restaurant at the Whitney Museum of American Art's Biennial exhibition. For the duration of the exhibit — which runs until May 30 — the temporary restaurant, called Sandwiched, is open inside the museum. Chefs from Meyer's empire, such as Floyd Cardoz of Tabla and Daniel Humm of Eleven Madison Park, have designed sandwiches for the menu, and pastry chefs from the restaurants have created sweets for the dessert list.

Underground? Probably not. But there are still plenty of wonderful things to eat — with an oh-so-trendy expiration date.